The contribution of hydrological fluxes to
carbon sequestration in a temperate forest
plantation
Kate Heal, Nick Forrest, Paul Jarvis
School of GeoSciences
The University of Edinburgh
Xiangqing Ma
Fujian Agriculture and Forestry University,
China
Research question
Proportion of C sequestered by forest
ecosystems lost in water flux?
Study site: Griffin Forest (56.6oN, 3.8oE)
• Catchment area 4.5 km2
• Dalradian schist overlain by humic gley/
stagnohumic gley soils
• Sitka spruce forest planted 1980-1981
Edinburgh
Field measurements of hydrological flux
April-December 2000
Storage raingauges x 5
Logging
raingauges x 2
Throughfall
& stemflow
samplers x
24 trees
Cloudwater gauges x 2
www.met-office.gov.uk
Ratings curve for Cultullich Burn, Griffin Forest 2000
log10 (Q) (l/s) = - 6.853 + 3.655 log10 (reading)
3.5
Regression
95% C I
P<0.001
S
R-Sq
R-Sq(adj)
log10 Q (l/s)
3.0
2.5
2.0
1.5
1.0
2.1
2.2
2.3
2.4
2.5
2.6
log10 reading (mV)
2.7
2.8
0.107552
97.8%
97.5%
CO2 flux (eddy covariance)
www.eastmain1.org/en/measuring-CO2-emissions.html
• Movement of air parcels
measured in 3 dimensions
using a sonic anemometer
• Air analysis with IRGA =>
flux of CO2 calculated
• Other micrometeorological
measurements to check
energy balance and
calculate evapotranspiration
Daily rainfall
Daily rainfall
500
000
500
000
500
-1
4000
0
3500
0
10
20
10
3000
30
20
2500
40
30
2000
50
1500
60
40
50
70
1000
80
60
500
90
70
0
100
J
F
M
A
M
J
J
A
S
O
N
D
80
Daily rainfall (mm)
000
Daily mean streamflow in 2000
Daily rainfall (mm)
500
Daily mean streamflow (l s )
000
Daily mean streamflow
Annual evapotranspiration estimates 2000
• Catchment water balance method:
E = precipitation – streamflow
Annual evapotranspiration
(mm)
• Eddy covariance:
800
E
Measured latent energy
Latent heat of energy of evaporation of water
600
400
200
0
Eddy covariance
Catchment water balance
• Estimates of evapotranspiration by
different methods show close
agreement
• Catchment water balance closure within
uncertainties
=> Confidence in measurements
of hydrological fluxes
Summary of chemical concentrations
Mean values; bars show max and min values
236 212
60
254 231
-1
C concentration (mg l )
Total C
Organic C
50
Inorganic C
40
30
20
10
0
Rainfall
Cloudwater
Throughfall
Stemflow
Soilwater
Streamwater
DOC vs flow relationship
Organic C concentration in streamwater vs log10 flow, 4 Apr-5 Dec 2000
Organic C streamwater (mg/l) = 1.101 + 1.863 log10 Q
8
S
R-Sq
R-Sq(adj)
Organic C (mg/l)
7
0.940832
58.5%
55.8%
P=0.001
6
5
4
3
1.0
1.5
2.0
2.5
log10 Q (l/s)
3.0
3.5
DOC flushed
from organic
near-surface
soil horizons at
high flows
Impact of C loss in river on net C sequestration
Parameter
Study site
Griffin Forest
(Scotland)
Hokkaido
(N Japan)
Moor House
(N England)
Shibata et al.
(2005)
Worrall et al.
(2003)
Sitka spruce
plantation
Temperate
deciduous forest
Heather (dwarf
shrub)
C loss in water (t
ha-1 a-1)
-0.026
-0.04 (incl. POC)
-0.348 (-0.149
without POC)
C sequestered (t
ha-1 a-1)
6.1
2.6
0.55
% sequestered C
lost in water
0.43
1.5
63 (27 without
POC)
Reference
Vegetation
Interaction between catchment C and N fluxes
• 73% of atmospheric N input removed by
canopy
• C sequestration per unit added N
(ΔC:ΔN)
– c.170 in 2000 at Griffin
– 210 (Magnani et al., 2007)
– 25 (De Vries et al., 2006)
• New NERC-funded project
– BACIP design with 2 adjacent sub-catchments
– 1 year before
– 4 years after: treatment with 40 kg N ha-1 yr-1
– (NH4NO3 4 x year, minimise water volume)
– Calculate ecosystem and catchment ΔC:ΔN
www.whrc.org